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Crossover from quantum to thermal behaviour in quantum spin liquids.

量子自旋液体中从量子行为到热行为的交叉。

基本信息

批准号：
1948688
负责人：
金额：
--
依托单位：
University of Cambridge
依托单位国家：
英国
项目类别：
Studentship
财政年份：
2017
资助国家：
英国
起止时间：
2017 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=studentship-1948688
关键词：
Crossover quantum thermal behaviour spin

项目摘要

Quantum spin liquids (QSLs) host a variety of exotic phenomena including fractionalisation, nontrivial braiding statistics of excitations, and the absence of long range order. While a number of candidate materials have been proposed, experimental detection of QSLs remains challenging due to the lack of any local order parameter. As part of the search for a `smoking gun' experimental signature, it is crucial to obtain a detailed understanding of the expected features characteristic of QSLs in well-established experimental techniques, including neutron scattering and NMR. We must therefore understand the interplay of spin liquid behaviour and the unavoidable presence of temperature, both at the theoretical level, and in terms of determining further potential experimental implications.Experimentally, the key characteristic of topologically ordered phases is their fractionalised excitations, such as the Laughlin quasiparticles of the fractional quantum Hall effect, or the magnetic monopoles of spin ice. At finite temperature, a finite density of these excitations will be excited thermally. This goal of this project is to study the effect that these excitations have on key system properties. First, we consider the entanglement content, as quantified by the logarithmic negativity, a recently proposed measure of mixed state entanglement. We show how an O(1) density of thermally excited quasiparticles leads to the demise, and eventually sudden death, of quantum correlations. In addition, we will study the dynamics of anyons at nonzero temperature. In particular, we hope to explore how the motion of one species of particle is affected by a background of thermally excited quasiparticles of a different species, when the two species obey nontrivial mutual braiding statistics. The long term goal of the project is to understand the effect of temperature on QSLs in general, with a particular focus on obtaining signatures of the T=0 QSL state in experimental data at nonzero temperatures.

量子自旋液体（QSL）的主机各种奇异的现象，包括分馏，非平凡的编织统计的激发，以及缺乏长程有序。虽然已经提出了一些候选材料，但由于缺乏任何局部序参量，QSL的实验检测仍然具有挑战性。作为寻找“确凿的证据”实验特征的一部分，必须详细了解在中子散射和核磁共振等成熟的实验技术中QSL的预期特征。因此，我们必须了解自旋液体行为和不可避免的温度的相互作用，无论是在理论水平上，并在确定进一步潜在的实验implications.Experimentally方面，拓扑有序相的关键特征是它们的分数激发，如分数量子霍尔效应的Laughlin准粒子，或自旋冰的磁单极子。在有限的温度下，有限密度的这些激发将被热激发。这个项目的目标是研究这些激励对关键系统特性的影响。首先，我们考虑纠缠的内容，量化的对数负，最近提出的衡量混合态纠缠。我们展示了热激发准粒子的O（1）密度如何导致量子相关性的消亡并最终突然消亡。此外，我们将研究任意子在非零温度下的动力学。特别是，我们希望探索如何运动的一个物种的粒子是由一个不同的物种的热激发准粒子的背景下，当两个物种服从非平凡的相互编织统计的影响。该项目的长期目标是了解温度对QSL的影响，特别关注在非零温度下获得实验数据中T=0 QSL状态的签名。